1. Field of the Invention
This invention relates to an attachment for sighting a weapon and more particularly to a low-profile illumination and laser sighting attachment having a single lens for receiving emission from both an illumination lamp and at least one aiming laser.
2. Background of the Relevant Art
Devices used for sighting or aiming a weapon, such as a firearm, are well known. Conventional aiming devices often involved a protrusion placed on the external surface of the firearm's barrel. Other aiming devices utilize magnifying scopes for more accurate placement of the firearm's output. These conventional sights generally require the user to view the target through the sight. Therefore, the weapon must be brought to eye level and within the line of sight of the user in order to be an effective aiming or sighting tool.
With the advent of the laser, it no longer is necessary that the weapon be fired at eye level but instead can be fired from, e.g., the hip. The laser therefore became a point of aim, point of impact sighting device. Wherever the laser impinges on the target is where the output of the weapon will strike. Thus, zeroing in on the target using a laser is accomplished much faster than conventional, non-laser methods.
An early laser aiming device is described in U.S. Pat. No. 4,212,109 to Snyder. Patent '109 describes the difficulty often encountered with adjusting or calibrating the placement of the lasers at the point of impact. Windage and elevation screws are shown placed on a bracket used to hold the laser housing to the weapon. By adjusting the position of the bracket with respect to the weapon, the laser output position is thereby moved to proper calibration. Unfortunately, since the bracket is exposed, there remains a possibility that the bracket as well as the adjustment screws can become jarred or caught on surrounding objects thereby inadvertently moving the laser sights out of calibration. Thus, there is a need for a laser aiming device which has its calibration mechanism protected from external objects to ensure reliable, long-term calibration.
A more recent laser aiming device is described in U.S. Pat. No. 5,064,988. Patent '988 not only uses a laser to aim the firearm, but also uses an illumination lamp to help illuminate the general target area. The lamp is therefore particularly suited for nighttime use for lighting the target area and targeting the laser beam on the lighted area. Moreover, the lamp can be covered with an infrared filter to prevent a live target from ascertaining the whereabouts of the weapon user. An infrared illumination combined with an infrared laser thereby achieves complete covert nighttime operation necessary in many military and law enforcement operations.
While the combination illumination and laser sighting device provides more flexibility for the user, conventional sighting devices are often large and bulky. Conventional combination devices such as that shown in Patent '988 require a rather large housing having two or more compartments. One compartment is used to house the lasers and the other compartment is used to house a battery pack. The battery pack is needed to power the illumination lamp while a separate battery pack operating at a different voltage is often required to power the lasers. Two separate compartments and two separate battery packs adds a considerable amount of size and weight to the combination device. Moreover, separate compartments with separate batteries operating at different output voltages increases considerably the cost in manufacture and operation of the device.
An additional problem associated with many conventional illumination and laser sighting devices is that the laser beam origination point is completely separate from the illumination path origination point. For example, as shown in Patent '988, a laser beam originates at a point above and completely outside the lamp source area. In order to maintain the lasers and lamp area dust-free and watertight, two separate lenses are needed--one lens for covering the lasers and the other lens for covering the illumination lamp. Not only does two separate lenses add to the cost of manufacture, but in addition, two separate lenses requires two separate infrared filters placed over each lens if complete nighttime operation is desired. One filter placed over the lamp ensures only infrared illumination while the other filter placed over the lasers ensures that the non-infrared laser does not emit detectable energy. To avoid using a filter over the lasers, an electrical switch can be added to selectively activate one laser as opposed to the other. However, the addition of the extra switch may only further increase the cost and size of the device.